@gradeexpectationscomics,
No, if you live in Canada, and sell items from Canada, as it appears you do, then you are do not have any income tax liability to the USA for your selling activity.
The tax liability situation in Canada is different. I would recommend that you search for some threads about this on the eBay Canada Community. There's are some good posts there that explain the tax situation for Canadians. As I understand it, if you are selling your personal possessions, you do not have to report it as income unless an item sells for more than a threshold amount, at which point you may have to report capital gains. Get the details on the eBay Canada community.
www.community.ebay.ca
One thing you do have to be aware of, is that if you sell more than a certain threshold, you may be required to register to collect and remit HST, so that's something that you want to be aware of before you reach that threshold.